Synthetic Roll Roofing Underlayment 4' x 250' Blue Color Replaces 15# Roofing Felt Liner Lighter Weight and 10x Stronger than Felt, 25 Year Warranty! 10x stronger than #15 felt: Can withstand higher wind conditions preventing blow offs & tears. Non-slip foot traction results in safer installs especially on steep slope roofs & windy weather Proprietary formulated anti-skid bottom coating to prevent underlayment slipping & shifting Will not absorb moisture, become brittle in cold or leach oil over life. 100% recyclable, containing post-industrial recycled polymers & impervious to mold growth